[PATCH] x86/IDT: Fix IDT generation for INT $0x80

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

When PV is enabled, entry_int80 needs to be DPL3, not DPL0.

This causes the XSA-259 PoC to fail with:

  --- Xen Test Framework ---
  Environment: PV 64bit (Long mode 4 levels)
  XSA-259 PoC
  Error: Unexpected fault 0x800d0802, #GP[IDT[256]]
  Test result: ERROR

(Clearly I have a bug in XTF's rendering of the error code too.)

Reported-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Luca Fancellu <luca.fancellu@xxxxxxx>
---
 xen/arch/x86/include/asm/gen-idt.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/x86/include/asm/gen-idt.h 
b/xen/arch/x86/include/asm/gen-idt.h
index 9c8810edf9d7..d1da73248c1c 100644
--- a/xen/arch/x86/include/asm/gen-idt.h
+++ b/xen/arch/x86/include/asm/gen-idt.h
@@ -77,7 +77,7 @@ GEN16(6);
 GEN16(7);
 
 #ifdef CONFIG_PV
-GEN(0x80, entry_int80,      DPL0, manual);
+GEN(0x80, entry_int80,      DPL3, manual);
 #else
 GEN(0x80, entry_0x80,       DPL0, autogen);
 #endif
-- 
2.39.5